Hydraulic brake



Feb. 1, 1938. c. BEUSCH v 2,101,257

'HYDRAULIC BRAKE I I I Filed Sept. 19, 1935 Patented Feb. 1, 1938 UNITED STATES PATENT OFFICE HYDRAULIC BRAKE Christian Beusch, Wadenswil, Switzerland Application September ,19, 1935, Serial No. 41,322

5 Claims.

This invention relates to vehicle brakes of the hydraulically actuated type and especially to improvements in parts of the brake system disclosed in my application Serial Number 33,906, filed July 30, 1935. In said prior application I have disclosed vehicle braking methods and devices in which two liquid systems are involved. The primary system is actuated by the operator and serves 'to apply a braking force to one or both brake shoes of one wheel only. The torque generated by the braking effect of the one wheel is utilized to operate the second liquid system to apply the brakes on the other wheels and possibly one of the brake shoes of the first wheel. The braking effect of the two fluid systems are so correlated that while the first wheel may be locked, the braking force applied to the other wheels is somewhat-less than that applied to the first wheel whereby the other wheels can not be locked. This is responsible for very favorable results in many respects, only three of which need be here mentioned. First, the force necessary to be applied by the operator-is many times less than would be necessary if all the wheels are braked directly. Second, since only one wheel.

may be locked skidding and swerving of the vehicle is not caused to any extent. Third, since all but one of the wheels are always braking with rolling friction instead of sliding friction practically the maximum braking effect is obtained.

As previously stated the braking torque of the first wheel is utilized to apply the brakes of the other wheels. This is done by applying the said torque force, whether backward or forward, to a liquid contained in a master chamber or cylinder by means of one or the other of a pair of pistons according to whether the direction of the braking is backward or forward. This pressure is transferred from the said master cylinder throughout the entire secondary fluidv system and ls utilized at each of the wheels to be braked thereby for applying an equal braking force on each of said wheels.

Now, it is essential to a satisfactory practical operation of such braking arrangements that both of the liquid circuits, primary andsecondary, shall at all times be entirely full of the braking liquid, but without excessive pressure. It will be realized that many factors tends to cause variation of the pressure in such systems for instance variations of temperature and atmosbe the cause, such variations of pressure must be promptly corrected.

The problem of maintaining the secondary system full of the braking liquid is somewhat complicated by the fact that the master cylinder 5 or cylinders must be provided with two pistons in order to provide for braking in both directions The present invention has for an object to provide a braking arrangement of the kind in question which will at all times be properly supplied 10 with ample force transmission fluid.

A further object of this invention is to provide a master cylinder or cylinders of the secondary liquid circuit of a braking system in which the pistons will consistently return to their 1 fully released position whenever the braking force applied thereto ceases.

A further object of this invention is to pro-- vide the master cylinder of the secondary liquid circuit with means for ensuring an adequate 20 supply of force transmission fluid.

Another object of the present invention is-to provide master cylinders for secondary circuits in which the forward and backward braking forces are applied in difierent chambers.

A further object of this invention is to provide simple and eflicient forms of master cylinders for vehicle brak ing systems and to provide with braking fluid.

Further objects and advantages of the invention -will be, apparent from the following detailed descriptipn and drawing of several em-v bodiments: representing the invention.

In the accompanying drawing, Fig. 1 is. a 35 diagrammatic representation of the type of braking system and apparatus to which the present invention relates; v

Fig. 2 is a side view partly in section of parts of the brake applying mechanism of a control- 40 ling wheel in which one brake shoe is operated by the secondary liquid circuit.

Fig. 3 is a side sectional view of one embodiment of a master cylinder.

Fig. '4 is a side sectional view of a second 46 embodiment of a master, cylinder chamber in which the two pistons operate in different communicating cylinders; and

Fig. 5 is a side sectional view of a third embodiment in which the two pistons operate in 50 separate cylinders.

In the vehicle braking system,

to whi h the present invention relates, two liquid systems 1 and I! are provided. The primary liquid system who applies pressure to the liquid in system 1 by pressing on pedal- I, which pivots lever 2 to push piston 3 to the right in cylinder 4. This presses the liquid through the primary system I into cylinder 9 where it presses pistons l6 apart and brake shoes II are forced into contact,

' mary liquid system is therefore always mainfor applying the brakes of the other wheels of-- tained full and free of undesired pressure regardless of changes in conditions tending to vary its pressure. 1

The brake shoes or jaws II are pivoted at points l2, l2 on a supporting frame I3 and are resiliently drawn toward eachother by spring II This frame is mounted on axle 6 and is capable of free rocking movement about the axle in either direction. 'lhe cylinder 9 is also mounted on this supporting frame l3. It .will be seen that when the brake shoes I l are moved into braking engagement with the brake drum of. the moving wheel a torque will be applied thereto and this will be transmitted to frame I3 through pivots. l2 and cylinder 3, and frame |3 will therefore tend to rotate-about the axle I in the direction of the force applied thereto. I

This tendency of frame II to rotate is used the vehicle and to this endframe I3 is provided with a pair of spaced extensions H the. inner faces of which engage the ends of operating rods '54, 56 of a pair of pistons or plungers 45, 46 in cylinder 4|. Cylinder 4| is securely mounted on a fixed part of the vehicle.

The cylinder 4| is the master cylinder of the secondary liquid system II, that is to say, pressure exerted on the liquid in cylinder I6 is applied to brake operating cylinders 2| at each of the other wheels to be braked. -Cylinder4| is connectedwith-each ofthe braking cylinders of the other wheels by conduit system l1 and each of the cylinders 2| applies or releases the associated pivoted brake shoes 23 in accordance with movements of pistons 22 in said cylinders in response to the fluid pressure and as influenced by tension springs connecting the various pairs of shoes.

In the modified construction shown in Fig. 2

ofthedrawlng,onlyonelu'akeshoe is'directly actuated by the primary liquid circuit. 'The other shoe or the controlling wheel is operated by the secondary system. To obtain this result the cylinder 3 of the first described arrangement is substituted by a double cylinder 26 fixed on the upper part of supporting frame I3. This cylinder is divided intermedially by a partitionwall so that in effect, it is two cylinders.

One of the chambers so provided is connected with the primary liquid system through pipe I,

and a plunger 23 in said cylinder actuates a brakeshoe The other chamber 23' of cylinder 26 is'connected with the master cylinder l6 of the secondary liquid system through conduit II. The other brake shoe ll of the controlling wheel is actuated by the pressure of the liquid of the secondary system acting on piston29' in chamber 23". Shoes II are resiliently urged to'ward'each other by interconnecting spring The chambers of cylinder 23 may'contain com- 7 springs 36, 3| interposed between the partition wall and the pistons for urging the pistons into bearing engagement with the outer ends of brake jaws l I. The features of the system of Fig. 2 not shown in the drawing are similar to those of the system of Fig. 1.

In order to maintain the proper volume of liquid in the secondary systemsiof the above described braking arrangements, in accordance with the present invention the secondary system master with if desired. Within the cylinder 41 are arranged a pair of pistonsor plungers 45, 46 nor mally spaced apart. A compression spring 41 yieldingly' biases the pistons apart. One of the pistons, for instance piston 45, is attached to a rod 50 which extends into one'end of the cylinder and is adapted to receive aworking force on its outer end from an arm H of the frame l3,

similarly as the rods of pistons of Figs. 1 and 2. The rod 50 is provided with a second piston 52 spaced from piston 45, whereby a chamber 53 is formed therebetween. Also a third piston or abutment 54 is formed or attached to rod 5|] at a position spaced from piston 52, forming .therebetween achamber 55.

- Piston 46 is attached or formed on the-end of rod 56 which extends outwardly through the opposite end of the cylinder 4| from the rod 56 and is adapted to be engaged at its outerend and operated by the other arm l4 of frame l3, (see Figs. 1 and 2). This rod is provided with a second piston or abutment 53 spaced'from piston 46 and forming therebetween a chamber 60.

When in non-operative position or when the opposite piston is operative the abutment pistons 54 and 58 engage the inwardly turned flanges 42,

43 respectively and limit the outward movement of their associated rods 56 and 56 respectively.

The pistons and abutments 54, 52, 45, 46 and 56,

which*are slightly'smallerthan the cylinder to allow free sliding therein, are provided on their inner face with sealing devices 62, 63, 64, 65 and 66 respectively for preventing undesired passage of fluid outwardly toward the ends of the cylinder 4|. 7

The space between the inner pistons and 46 is connected with the 'secondary' liquid system I! through a port 68. When one or the other of the rods or 56 is pushed'inwardly, theother is held against yielding by its abutment engaging a flange at the ends of the cylinder and consequently a pressure .is generated in the chamber 16 between the inner pistons and transmitted to the secondary liquid system H.

Chamber "I0 is connected with chamber 53 through a conduit 1| formed in the wall of cylinder 4|. One end 12 of this conduit opens to chamber 10 closely adjacent piston 46 when in its outer position, whereby a very slight inward movement of -piston 46 seals this'end of the conduit. The other end 12' of the conduit 1| opens into chamber. 52. Chamber 53 also communicates with reservoir by an opening 15 which opens into chamber 53 close to piston 52 whereby a slight inward movement of piston 52 immediately closes opening 15. It is clear that if either rod 56 or 56 moves inwardly communication between reservoir 44 and chamber III is immediately interrupted while upon return to its outer position communication is immediately reestablished. Therefore, each time the brakes are released the secondary liquid system is equalized and corrected if necessary to the proper pressure and volume and will at all times be automunicating with each other at their inner ends but having their axes angularly disposed with respect to each other. In thiscase a pairof compression springs 41 are provided and their inner ends, opposite the pistons, abut against abutments 80, 8|. The two cylinders are in communication with each other, when the brakes are released, by means of a conduit H formed in the-cylinder casing, and opening into cylinder 4| at a point immediately in rear of its innermost piston and into cylinder ll" at a point immediately in front of its innermost piston. The reservoir 44' may be formed separately from the cylinders and communicate therewith by conduit 15' opening into cylinder 4| at a point between pistons 45'- and 52. End sealing and abutment engaging pistons 54' and 58 are provided in this embodiment also, and engage abutments 42' and 43'. This embodiment is otherwise similar to that of Fig. 3 and further descrip-" tion thereforeappears unnecessary.

The embodiment shown in Fig. 5 is also similar in principle to that of Fig. 3, but is provided with a pair of separate cylinders and reversed pistons. The working chambers 10' and 10" of the cylinders483, 84 respectively are at the outer ends of the cylinders and are in communication through conduit 85. This conduit 85 is in connection with a secondary braking system 86 corresponding to system I! of Fig. 1 or H of Fig. 2. The inner ends of the cylinders are provided with inwardly extending abutment flanges 42, 43", against which abutment pistons 54", 58" respectively may engage. In this embodiment the rods 56' extend toward each other into or substantially into engagement with an arm 90 of a frame 9| pivotally attached to the axle of the vehicle and influenced by braking torque of a controlling wheel similarly as frame [3 of Figs. 1 and 2. Instead of apair of arms It as on frame l3, only a singlearm 90 need be provided on the frame 9|.

Chamber l0 communicates with chamber 53' by means of a conduit 1 l which opens into these chambers at points corresponding to the quivalent points in chambers 10 and 53 of Fig. 3 and'for the same purpose. 'Chainber 53' also communicates with a reservoir 44" through port 15" when non-operative.

It will be apparent that the connections and principles of operation of each of the above described embodiments are similar, and that in each case the secondary liquid system is put into communication with the pressure and volume equalizing reservoir each time the brakes are fully released.- However, immediately upon operation of the mechanism in either direction the reservoir is tightly closed off from the system so that no leakage thereto can occur. The system is thereby maintained in proper working order at all times.

I claim:- I

1. A master chamber forvehicle wheel hydraulic brake actuation comprising a cylinder.

having a pair of pistons,one of said pistons being located in said cylinder having a forward and a rearward packing ring, and having a fluid passage between said rings, a reserve fluid reservoir connected with said fluid passage closely adjacent said rearward-packing ring, and aconduit'connectin'g the passage between said rings with a point in the chamber closely adjacent and in front of the other piston, said other piston having a packing ring, whereby the initial part of a brake applying movement of either of said pistons seals the master chamber from the reservoir, and communication between said chamber and reservoir is established each time both pistons move to full release position. X

2. A master chamber for hydraulic brake systems for vehicle wheel brakes,'comprising a cylinder, oppositely facing pistons in said cylinder, said cylinder and pistons defining a control space of variable capacity, according .to the positions of the pistons, means for positively limiting movement of each of said pistons in said cylinder in the directions which expand the control space, means connecting the hydraulic system with said control space, means for moving one or the other of said pistons in a direction to reduce the capacity of said control space depending on the direc.-

tion of braking of the vehicle, and pressure equalizing and adjusting means for said control space a. id system comprising a braking fluid reservoir, conduits connecting the reservoir with the control space when both of said pistons are in the position of maximum expansion ofthe control space and means for interrupting com-- munication between said reservoir and control space when either of said pistons is in a position reducing the capacity of said control space;

3. A master cylinder for hydraulic brakes for vehicle wheels comprising a. cylinder, a rod extending into one end of said cylinder, and having three spaced pistons each provided with a sealing ring engaging the inner wall of said cylinder, the spme between the inner and intermediate sealing rings constituting a fluid passage, a second rod extending into said cylinder from the opposite end from the first rod, said second rod having two pistons each provided with a sealing ring engaging the inner surface of the cylinder, means to limit the outward movement of said rods, a fluid supply and equalization reservoir, a conduit connecting said reservoir with said cylinder at a .point adjacent the passage between the inner and intermediate sealing rings of the first rod and. closely adjacent the intermediate ring, the wall of said cylinder having a passage extending from said mentioned passage to a point adjacent the inner side of the sealing ring'ofthe inner piston of the other rod, means yleldingly pressing the rods toward their outermost positions, and a hydraulic system connected with said cylinder at a point intermediate the two inner pistons.

4. A master cylinder for hydraulic brakes for vehicle wheels comprising a casing provided with a pair of cylindrical openings angularly disposed with respect to each other directed toward each other and communicating at their inner ends, a rod extending into one of 'said openings, said rod having three spaced pistons each provided with a fluid sealing ring engaging the inner wall I of the opening in which they are located, the

space between the inner and intermediate-seal- .ing rings constituting afluid passage, a second rod extending into the other cylindrical opening, said second rod having two pistons each provided with a sealing ring engaging the inner surface of the opening in which they are located, the outer ends of said openings extending inwardly, the

outermost pistons on each of said rods engaging said inward extensions and limiting the outward movement of said rods, a fluid supply and equalization reservoir, a conduit connecting said reservoir with the first mentioned cylindrical opening at a point adjacent the passage between the inner and intermediate sealing rings of the first rod and closely-adjacent said intermediate ring, said casing having a passage extending from said first mentioned passage to the second opening at a point closely adjacent the inner side of the sealing ring of the inner piston of the other rod, means yieldingly pressing the rods toward their outermost positions, and a hydraulic system connected with said casing at a. point intermediate the two inner pistons.

5. In a. master hydraulic pressure chamber for controlling vehicle wheel brakes, a pair of aligned cylinders spaced apart. one of said cylinders having a rod extending thereon from the direction of the other cylinder, said rod having three spaced pistons disposed thereon each of which is provided with a fluid sealing ring, the space between the inner and intermediate sealing rings constituting a fluid passage, the end of said cylinder toward the other cylinder having an inwardly extending flange against which the outer' piston abuts to limit the outward movement of said rod, the other end of said first cylinder being closed, a second rod extending into the second cylinder from the direction of the first cylinder, said second rod having two spaced pistons thereon within the second cylinder, each 01 said pistons having a fluid sealing ring engaging the inner surface of said secondcylinder, the end of said second cylinder enteredby said second rod having astop against which the outermost of said two'pistons engages to limit the outward movement of said second rod, the other end of said second cylinder being closed, a conduit connecting the opposite ends of said cylinders with each other and with a hydraulic brakesystem, means or the other thereof according to the direction of a braking efiect.

CHRISTIAN BEUSCH.

for supplying Land equalizing fluid in said system, 

